Novel modern terrestrial analogues for potential life-favouring environments on ancient Mars

随着2020年火星探测器毅力号的着陆，新一代的火星研究成为可能。这次任务将从耶泽洛陨石坑带回样本，包括那些可能潮湿的环境（例如，由蒙脱石粘土和碳酸盐序列证明），因此在火星过去可能适合居住。代理开发的巨大进步为重建地球上过去的微生物生态、pH和碱度打开了窗口。我们建议将这些进展扩展到火星样本，但这样的努力将需要在地球类似物中进行新一代古代理验证和校准。这些模拟地点包括著名的碱性环境，这些环境仍未使用计划中的方法进行勘探：冰岛的Myvatn湖，澳大利亚的库荣沿海泻湖和土耳其的Salda湖。该学生将使用i)有机生物标志物来揭示与高碱性环境相关的生态环境；ii)硼和氮同位素分析来提供pH和碱度条件的观点。其他生物标志物（如甘油醚脂类）将进一步限制ph值。这些参数将有助于确定火星上过去潜在生命的条件，并扩大生物特征的可能性，特别是在未来几年火星样本被送回我们的实验室并进行分析之后。总体目标是开发一种跨学科的策略来探索古代火星上可能的微生物生态，强调从火星潮湿的过去假设的碱性环境，并在地球上显示，已知存在大型多样的微生物群落。这项研究还广泛地说明了土卫二等高ph值天体的可居住性和系外行星水世界作为寻找外星生命的目标。

With the landing of the Mars2020 rover Perseverance, a new generation of Martian research is possible. This mission will return samples from Jezero crater, including those from settings that were likely wet (e.g., as evidenced by smectite clays and carbonate sequences) and therefore possibly habitable in the Martian past. Tremendous strides in proxy development have opened up windows to reconstructing past microbial ecology, pH and alkalinity on Earth. We propose to extend these advances to Martian samples, but such efforts will require a new generation of paleo-proxy validation and calibration in terrestrial analogues. These analogue locations include famous alkaline settings that remain unexplored using the planned methods: Lake Myvatn in Iceland, the Coorong coastal lagoon in Australia, and Lake Salda in Turkey. The student will use i) organic biomarkers to reveal ecologies associated with highly alkaline setting and ii) boron and nitrogen isotope analysis to provide perspectives of pH and alkalinity conditions. Additional biomarkers (e.g. glycerol ether lipids) will provide further constraints on pH. These parameters will help define the conditions of potential past life on Mars and expanded possibilities for biosignatures, particularly once Martian samples are returned and analysed in our labs in the coming years. The overarching goal is to develop an interdisciplinary strategy for exploring possible microbial ecology on ancient Mars, emphasizing alkaline settings that are hypothesised from Mars' wet past and shown on Earth are known to harbour large and diverse microbial communities. This study also speaks broadly to habitability on high-pH bodies such as Enceladus and exoplanetary water worlds as targets in the search for extraterrestrial life.